As I revealed earlier this week, it is housebuilding that will the central theme of Ed Miliband's speech tomorrow. The Labour leader will pledge to build one million new homes over the course of the next parliament in the biggest building programme for a generation.

All three of the main parties have identified housing as one of the defining political issues of the moment but while the coalition's Help To Buy scheme is inflating demand, it does little to address what Miliband rightly calls the "fundamental problem" of supply. He will announce that Sir Michael Lyons, the former council chief executive and former BBC Trust chairman, will chair a Rebuilding Britain Commission to locate sites for new towns and garden cities akin to Milton Keynes and Welwyn Garden City. The commission will also introduce a new "right to grow" status which will force town halls to draw up housebuilding plans with neighbouring councils. In addition, Miliband will pledge to tackle the problem of land-banking by giving councils the power to charge developers for sitting on land with planning permission, or to issue compulsory purchase orders.

As a policy, a mass housebuilding programme ticks all the boxes: it is easy to explain and offers a powerful dividing line with the Tories. It would stimulate growth and employment, help to bring down long-term borrowing (for every £100 that is invested in housebuilding £350 is generated in return) and reduce welfare spending. It would be a literal fulfilment of Labour's pledge to "rebuild Britain" after austerity, just as the 1945 government did after the war. Jack Dromey, the shadow housing minister, said: "The next Labour government will tackle Britain’s housing crisis by building homes on a scale no government has done for a generation and in doing so creating hundreds of thousands of jobs and apprenticeships." After months in which many of Miliband's supporters have lamented the absence of a signature policy, this could well be the political game-changer he so badly needs.

In an attempt to position Labour as the party of small business, Miliband will also announce a £790m cut in tax rates for smaller firms, funded by reversing the planned cut in corporation tax from 21% to 20% in 2015. The cut in business rates would apply to 1.5 million businesses with an annual rental value of £50,000 or less, saving firms an average of £450 a year and as much as £2,000. Upon entering office in 2015, Labour would return rates to their 2014 level and then freeze them in 2016. It would also reconsider the coalition's decision to postpone the business rate revaluation until 2017, which will benefit prosperous parts of the country at the expense of poorer ones.